Inflammatory diseases of the heart and associated membranes such as myocarditis and pericarditis are becoming increasingly associated with virus infections. Direct isolation and serologic analyses of IgM or IgG levels in many adults and children with heart inflammatory diseases have demonstrated a close association with the group B coxsackieviruses (CB). The role of any of the six serotypes of CB viruses is unknown; however, two basic hypotheses for the role of CB viruses in myo/pericarditis have been developed. The first suggests that the inflammatory reactions are due primarily to replication of CB viruses and the distruction of the heart myocytes. The second hypothesis suggests that the inflammatory reaction is due to immunological consequences of the virus being present and, perhaps, persistently infecting the myocytes and cells of the associated membranes. This proposal seeks to identify and isolate CB3 virus receptors in heart cells from mice known to have propensity to severe myocarditis (Balb/c strain) and from an amyocardiogenic variety (C57B1 strain). The isolated CB3 receptors will be compared electrophoretically and biochemically to the CB3 receptor which will be isolated from HeLa cells. Three methods to identify the cell receptors will be developed: direct isolation from plasma membranes using a specific virus receptor assay, isolation from CB3-cell complexes using deoxycholate and Triton X-100, and isolation from virus-cell complexes with the receptor specifically identified by label transfer crosslinking. With a receptor: anti- receptor system available, antiviral agents effective in other enterovirus systems will be tested, in the long term, for their ability to interfere with virus-cell binding. Also, its receptor mutants of CB3 will be generated and isolated by replicate plating techniques and studied at permissive and non-permissive temperatures for binding to the isolated cell virus-receptor complex and specific receptor polypeptides which are isolated.